Propeller drive mechanism for a model airplane

ABSTRACT

A propeller drive mechanism for a model airplane is disclosed, wherein a guide plate with guide grooves is rotatably mounted on a shaft in coupling with an output shaft of a drive motor, and clutch pins are fitted into the guide grooves so that the clutch pins may be protruded under the effect of centrifugal force. A clutch member to which a propeller is secured has shoulders for engaging with the clutch pins in their protruded position to receive drive force and a cam face for rendering the clutch pins inoperative to the clutch member.

Umted States Patent 1 1111 3,744,180 Mabuchi 14 1 July 10, 1973PROPELLER DRIVE MECHANISM FOR A 2,333,007 10/1943 Heintz 192/46 MODELAIRPLANE 1,466,394 8/1923 Fornaca.. 192/42 X 268,471 12/1882 51110::192/46 x Inventor: Kenlchl Mabuchl, y Japan 2,025,239 12/1935 Henning192/46 x Assigneez Mabuchi Motor Ltd. y 2,330,677 9/1943 Canfield19,2/46

Japan Primary Examiner-Benjamin W. Wyche [22] 1971 Att0meyStaas, Halsey& Gable [21] Appl. No.2 204,038

5 71 ABSTRACT [30] Foreign Application Priority Data Dec 3 1970 Ja an45/106297 A propeller dr1ve mechamsm for a model airplane is pdisclosed, wherein a guide plate with guide grooves is 52] U 5 Cl 46/7846/243 v 192/46 rotatably mounted on a shaft in coupling with an output192/105 BB 41 6/169 shaft of a drive motor, and clutch pins are fittedinto [51] ML Cl. 716d 41/00 6d 43 4 the guide grooves so that the clutchpins may be pro- [58] Field 192/105 BB 42 46 truded under the effect ofcentrifugal force. A clutch 'I;{ 46/78 member to which a propeller issecured has shoulders for engaging with the clutch pins in theirprotruded po- [56] References Cited sition to receive drive force and acam face for render- UNITED STATES PATENTS ing the clutch pinsinoperative to the clutch member.

233,637 l0/ 1880 Passmore 192/46 1 Claim, 4 Drawing Figures PROPELLERDRIVE MECHANISM FOR A MODEL AIRPLANE The present invention relates to apropeller drive mechanism, and more particularly to a propeller drivemechanism for a model airplane which is applicable to any type of powersource such as rubber resilient power, electric motor, gasoline engineor the like.

It is an object of the present invention to provide a propeller drivemechanism in which power is automatically and positively transmitted andthe transmission of the power is automatically shut off simultaneouslywith the halt of a power motor.

It is another object of the present invention to provide a propellerdrive mechanism for a model airplane which has a very small frictionalresistance during driving and effects smooth driving of the propeller.

It is other object of the present invention to provide a propeller drivemechanism for a model airplane which is simple in structure, economic tomanufacture, fail-safe, and durable over extended period.

According to the present invention, the above and other objects of thepresent invention is accomplished by a propeller drive mechanism for amodel airplane wherein a guide plate having a guide grooves thereon isrotatably mounted on a shaft and coupled to an output shaft of a drivemotor, clutch pins which are adapted to be protruded under the effect ofcentrifugal force are fitted into said guide grooves, and a clutchmember to which a propeller is attached is formed with shoulders whichengage with the clutch pins when the latter are protruded to receivedrive power and a cam face for rendering the clutch pin inoperative tothe clutch member.

A preferred embodiment of the present invention will now be described inmore detail with reference to the accompanying drawings, in which;

FIG. 1 is a longitudinal section view of a preferred embodiment of apropeller drive mechanism for a model airplane in accordance with thepresent invention,

FIG. 2 and FIG. 3 are enlarged sectional views illustrating clutchportions, and

FIG. 4 is an exploded perspective view of major parts.

In the drawings, a miniature electric motor 1 is fixedly mounted on aframe 3 secured to the body of model airplane (not shown) in anappropriate manner. A shaft 1 of the motor projects through the frame 3and has a pinion la fixedly mounted thereon at its end. A shaft 2 isrotatably supported on the frame 3 in parallel with the motor shaft 1'by means of thrust bearings 3a. The shaft 2 extends at one end outwardlyfrom the frame 3. A gear wheel 4 is rotatably mounted on the shaft 2 andmeshed with the smaller toothed wheel la. The gear wheel 4 has a guideplate 4a integrally connected on one side of the gear wheels 4. Theguide plate 4a has two guide grooves 4a extending radially outwardlyfrom the center thereof. It should be understood that the number of theguide grooves 4a, need not be two but it may be three or four or evenone provided that a balance requirement is met. The reference numeral 4brepresents clutch pins, which are slidably fitted into said guidegrooves 4a,

Each clutch pin 4b has at one end a concaved groove to be in contactwith the outer face of the shaft 2 and at the other end forms a tip endand a concaved and inclined face downwardly extending therefrom, theinclination being made in a direction contrary to the rotation of thegear wheel 4.

A disc 5 is mounted on the shaft 2 such that it contacts the guide plate4a face to face to cover the guide grooves 4a,. A propeller 6 is mountedon the sleeve 7a which is fixedly secured by a nut 7d threadedly engagedwith the threaded end of the sleeve and against a shoulder formed in thesleeve 7a. A clutch member 7 is integrally connected to the sleeve 7aand has an inner surface. The inner surface has a shape composed of twosemi-circular cam faces 70 and two shoulders 7b connecting the faces.The number of the cam faces 70 and shoulders 7b may be changed inaccordance with the number of the guide grooves 4a and the clutch pins4b.

Nuts 2a and 2b are threadedly engaged with the shaft 2 at its oppositeends to secure the mounted elements therebetween.

With the construction described above, as the smallsize motor 1, thegear wheel 4 is rotated through the pinion la. The rotation of the gearwheel 4 causes the clutch pins 4b, which were fitted into the guidegrooves 4a, of the guide plate 4a, to be protruded radially outwardly,as shown in FIG. 3, under the effect of centrifugal force so that thetip ends of clutch pins 4b abut against the shoulders 7b of the clutchmember 7 to thereby drive the propeller 6. When the rotation of theminiature electric motor 1 is stopped, the rotation of the gear wheel 4is also stopped and the propeller 6 continues to rotate by its inertiaforce and air resistance. However during the first complete rotation ofthe propeller 6 after the halt of the rotation of the gear wheel 4 theclutch pins 4b are pushed back radially inwardly by the cam face 70 toassume the position shown in FlG. 2. If the outer end of the clutch pinshas the convexed and inclined surface as described above and shown inthe drawing, linear contact with the cam face 7c is provided, whichresults in further decrease of frictional resistance.

As described above, by the use of the clutch pins adapted to beprotruded under the effect of centrifugal force and by the fact that thedrive power is transmitted through the engagement of the protruded pinswith the shoulders of the clutch member, the transmission of the drivepower can be effected automatically and positively and it can beautomatically interrupted simultaneously with the halt of the motorrotation with a very small frictional resistance after interruption.Namely, if the tip ends of the clutch pins rest at deep points in thecamming groove no frictional resistance occurs there and even when theyrest at relatively shallow points frictional resistance is very lowpermitting smooth drive said sleeve, a clutch member formed as a part ofsaid sleeve, said clutch member being provided with a cavity withinwhich said guide plate fits, said cavity comprising opposed cam facesinterrupted by opposed shoulders such that as said motor drives saidshaft said clutch pins move outwardly under the influence of centrifugalforce engaging and locking with said shoulders of said clutch membercausing said sleeve and propeller to rotate.

1. A propeller driving mechanism for a model airplane, comprising: amotor; a shaft mounted to the model airplane for rotation; A gear wheelfixedly mounted to said shaft, means operably connecting said gear wheeland said motor such that said shaft is driven by said motor; a guideplate mounted to said shaft adjacent said gear wheel, said guide plateincluding oppositely disposed grooves extending outwardly from saidshaft to the outer periphery of said guide plate; clutch pins slidablymounted within said grooves; and a sleeve operably mounted for rotationabout a portion of said shaft, a propeller fixedly mounted to saidsleeve, a clutch member formed as a part of said sleeve, said clutchmember being provided with a cavity within which said guide plate fits,said cavity comprising opposed cam faces interrupted by opposedshoulders such that as said motor drives said shaft said clutch pinsmove outwardly under the influence of centrifugal force engaging andlocking with said shoulders of said clutch member causing said sleeveand propeller to rotate.